在文本视图中显示从毫秒转换的时间

我正在制作一个计时器应用程序。根据我现在所拥有的，用户可以从微调器中选择：小时、分钟和秒。我有一个公式，可以将计时器的总选择时间转换为毫秒。时间也应该转换成字符串并显示出来。问题是没有显示任何内容。TextView倒计时应以小时、分钟和秒为单位显示时间。

using System;
using System.Timers;
using Android.App;
using Android.Content;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.OS;
namespace QuickTimer
{
    [Activity(Label = "QuickTimer", MainLauncher = true, Icon = "@drawable/icon")]
    public class Activity1 : Activity
    {
        private TimeSpan _ts;
        private Timer _timer = new Timer();
        private int _counter;
        private string _time;
        private int _convertHours;
        private int _convertMinutes;
        private int _convertSeconds;
        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);
            // Set our view from the "main" layout resource
            SetContentView(Resource.Layout.Main);
            Button buttonSet = FindViewById<Button>(Resource.Id.setButton);
            buttonSet.Click += setButton_Click;
            Spinner spinnerHours = FindViewById<Spinner>(Resource.Id.spinnerHours);
            spinnerHours.ItemSelected += new EventHandler<AdapterView.ItemSelectedEventArgs>(spinnerHours_ItemSelected);
            var adapterHours = ArrayAdapter.CreateFromResource(
                this, Resource.Array.hoursArray, Android.Resource.Layout.SimpleSpinnerItem);
            adapterHours.SetDropDownViewResource(Android.Resource.Layout.SimpleSpinnerDropDownItem);
            spinnerHours.Adapter = adapterHours;
            Spinner spinnerMinutes = FindViewById<Spinner>(Resource.Id.spinnerMinutes);
            spinnerMinutes.ItemSelected += new EventHandler<AdapterView.ItemSelectedEventArgs>(spinnerMinutes_ItemSelected);
            var adapterMinutes = ArrayAdapter.CreateFromResource(
                this, Resource.Array.minutesArray, Android.Resource.Layout.SimpleSpinnerItem);
            adapterMinutes.SetDropDownViewResource(Android.Resource.Layout.SimpleSpinnerDropDownItem);
            spinnerMinutes.Adapter = adapterMinutes;
            Spinner spinnerSeconds = FindViewById<Spinner>(Resource.Id.spinnerSeconds);
            spinnerSeconds.ItemSelected += new EventHandler<AdapterView.ItemSelectedEventArgs>(spinnerSeconds_ItemSelected);
            var adapterSeconds = ArrayAdapter.CreateFromResource(
                this, Resource.Array.secondsArray, Android.Resource.Layout.SimpleSpinnerItem);
            adapterSeconds.SetDropDownViewResource(Android.Resource.Layout.SimpleSpinnerDropDownItem);
            spinnerSeconds.Adapter = adapterSeconds;
            _timer.Interval = 1000;
            _timer.Elapsed += new ElapsedEventHandler(OnTimedEvent);
            _timer.Enabled = true;
        }
        private void setButton_Click(object sender, EventArgs e)
        {
            TextView countdown = (TextView)FindViewById(Resource.Id.countdown);
            countdown.Text = getTime();
        }
        public string getTime()
        {
            return _time;
        }
        private void OnTimedEvent(object sender, ElapsedEventArgs e)
        {
            _counter = (getConvertedTime()/1000);
            Console.WriteLine(getConvertedTime());
            for (int i = 0; i <= 5/*(getConvertedTime()/1000)*/; i++)
            {
                _ts = TimeSpan.FromSeconds(_counter);
                string _time = string.Format("{0:D2}h:{1:D2}m:{2:D2}s:{3:D3}ms",
                    _ts.Hours,
                    _ts.Minutes,
                    _ts.Seconds,
                    _ts.Milliseconds);
                Console.WriteLine(_time);
                _counter--;
            }
            if (_counter == 0)
            {
                _timer.Enabled = false;
            }
        }
        public int getConvertedTime()
        {
            int convertedTime = _convertHours + _convertMinutes + _convertSeconds;
            return convertedTime;
        }
        private void spinnerHours_ItemSelected(object sender, AdapterView.ItemSelectedEventArgs e)
        {
            Spinner spinnerHours = (Spinner)sender;
            int hours = Int32.Parse(spinnerHours.SelectedItem.ToString());
            _convertHours = hours * 1000 * 3600;
            string toast = string.Format("", spinnerHours.GetItemAtPosition(e.Position));
            Toast.MakeText(this, toast, ToastLength.Long).Show();
        }
        private void spinnerMinutes_ItemSelected(object sender, AdapterView.ItemSelectedEventArgs e)
        {
            Spinner spinnerMinutes = (Spinner)sender;
            int minutes = Int32.Parse(spinnerMinutes.SelectedItem.ToString());
            _convertMinutes = minutes * 1000 * 60;
            string toast = string.Format("", spinnerMinutes.GetItemAtPosition(e.Position));
            Toast.MakeText(this, toast, ToastLength.Long).Show();
        }
        private void spinnerSeconds_ItemSelected(object sender, AdapterView.ItemSelectedEventArgs e)
        {
            Spinner spinnerSeconds = (Spinner)sender;
            int seconds = Int32.Parse(spinnerSeconds.SelectedItem.ToString());
            _convertSeconds = seconds * 1000;
            string toast = string.Format("", spinnerSeconds.GetItemAtPosition(e.Position));
            Toast.MakeText(this, toast, ToastLength.Long).Show();
        }
    }
}